1. Field of the Invention
The present invention relates to a switchable transparent electrowetting display device, and more particularly, to a switchable transparent electrowetting display device in which the transparency and the grey scale value of different sub-pixel regions can be controlled independently.
2. Description of the Prior Art
Electrowetting display device has been expected to be a potential product in display industry for its high aperture ratio and it does not require polarizer sheet. Please refer to FIG. 1. FIG. 1 is a schematic diagram illustrating a conventional electrowetting display device. As shown in FIG. 1, the conventional electrowetting display device 10 includes an electrowetting display panel 20 and a back light module 30. The electrowetting display panel 20 includes two transparent substrates 21, 22 disposed oppositely, a polarized water solution 23 disposed between the transparent substrates 21, 22, a hydrophobic dielectric layer 24, a transparent electrode 25, partitions 26, and ink layers 27 having different colors e.g. red ink layer 27R, green ink layer 27G and blue ink layer 27B. When a voltage source 28 provides a voltage between the transparent electrode 25 and the polarized water solution 23, the surface tension between the hydrophobic dielectric layer 24 and the polarized water solution 23 is modulated such that the locations of the ink layers 27 can be controlled. Consequently, after a white light LW generated by the back light module 30 passes through the ink layers 27 of different colors, a red light LR, a green light LG and a blue light LB having different grey scale values can be provided to exhibit full-color display effect.
However, the conventional electrowetting display device 10 is not able to provide transparent display effect. Also, the contrast ratio of the conventional electrowetting display device 10 is poor since the user will see the white light LW that does not pass through the ink layers 27 when displaying. As a result, the dark image displayed by the electrowetting display device 10 is not black enough.